RedShift: Transparent SNARKs from List Polynomial Commitments

We introduce an efficient transformation from univariate polynomial commitment based zk-SNARKs to their transparent counterparts. The transformation is achieved with the help of a new IOP primitive which we call a list polynomial commitment. This primitive is applicable for preprocessing zk-SNARKs over both prime and binary fields. We present the primitive itself along with a soundness analysis of the transformation and instantiate it with an existing universal proof system. We also present benchmarks for a proof of concept implementation alongside a comparison with the current non-transparent state-of-the-art. Our results show competitive efficiency both in terms of proof size and generation times. At the 80-bit security level, our benchmarks provide proof generation times of about a minute and proof sizes of around 515 KB for a circuit with one million gates.